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PubMed2006

Image, imagination, and reality: on effectiveness of introductory work with vocalists.

Fifty-four sung tokens, each consisting of eight images were generated with the help of magnetic resonance imaging (MRI) technique to demonstrate the work of intrapharyngeal muscles when singing and speaking, and to help the educational process. The MRI images can be used as a part of a visualization feed-back method in vocal education and contribute to creation of proper mental images. The use of visualization (pictures, drafts, graphs, spectra, MRI images, etc.), along with mental images, facilitates simplification and acceleration of the process of understanding and learning how to master the basics of vocal technique, especially in the initial period of study. It is shown that work on muscle development and use of imagination should progress with close interaction between the two. For higher effectiveness and tangible results, mental images used by a vocal pedagogue should correspond to the technical and emotional level of a student. Therefore, mental images have to undertake the same evolution as articulation technique-from simplified and comprehensible to complex and abstract. Our integrated approach suggests continuing the work on muscle development and use of imagination in singing classes, employing the experience of voice-speech teachers. Their exercises are modified using the empirical method and other techniques developed creatively by singing teachers. In this method, sensitivity towards the state of the tissues becomes increasingly refined; students acquire a conscious control over the muscle work, students gain full awareness of both sensation and muscle activity. As a result, a complex of professional conditioned reflexes is being developed. A case study of the New Zealand experience was conducted with groups of Maori and European students. Unique properties and trends in the voices of Maori people are discussed.

Humans↗
PubMed1991

Complex cellular and subcellular regulation of notch expression during embryonic and imaginal development of Drosophila: implications for notch function.

The Notch gene in Drosophila encodes a transmembrane protein with homology to EGF that appears to mediate cell-cell interactions necessary for proper epidermal vs. neural fate decisions. In this study, we examine Notch expression in detail throughout embryonic and imaginal development using confocal laser-scanning microscopy and specific mAb probes. We find that Notch is expressed in a tissue-specific manner as early as the cellular blastoderm stage, when cells of the presumptive mesoderm clearly express less Notch than adjacent ectodermal precursors. Notch is abundantly expressed during the initial determination of neuronal lineages, such as the embryonic neuroblasts and the precursors of sensory neurons in the imaginal disc epithelia, but expression quickly decreases during subsequent differentiation. These changing patterns of Notch expression do not correlate well with cell movements, and thus do not appear to support the notion that the major function of Notch is to maintain epithelial integrity via adhesive mechanisms. Our data suggest instead that Notch may act as a cell-surface receptor, perhaps functioning in the lateral inhibition mechanism that is necessary for proper spacing of neuronal precursors.

Animals↗
PubMed1969

Maintenance of imaginal discs of Drosophila melanogaster in chemically defined media.

A phosphate-buffered saline and a chemically defined synthetic medium for in vitro maintenance of imaginal discs of Drosophila melanogaster were developed. The composition of the chemically defined medium was varied in order to optimize the incorporation of tritiated uridine into RNA and tritiated amino acids into acid-insoluble protein. The optimal ranges obtained were: pH, 6.75-7.35; osmolarity, 285-345 milliosmoles/liter; sodium concentration, 40-60 mM/liter; potassium concentration, 40-60 mM/liter; magnesium concentration, 0.5-3.5 mM/liter; calcium concentration, 0.3-1.5 mM/liter; and inorganic phosphate concentration, 1.5-4.0 mM/liter. The phosphate-buffered saline is superior to a commonly used insect Ringer solution in maintaining total RNA and acid-insoluble protein synthesis in culture. The chemically defined synthetic medium permits linear total RNA and acid-insoluble protein synthesis for more than 48 hr, DNA synthesis for several hours, normal differentiation to occur after 74 hr in vitro, and trypsinization of imaginal discs into single cell suspensions without developmental damage.

Amino Acids↗
PubMed1989

A tripartite interaction among alleles of Notch, Delta, and Enhancer of split during imaginal development of Drosophila melanogaster.

A dramatic example of a phenotypic interaction that involves neurogenic loci during Drosophila imaginal development is the synergistic impact of split (spl), a recessive allele of the Notch locus, and E(spl)D, a dominant gain-of-function allele of the Enhancer of split locus, on morphogenesis of the compound eye. Screens for mutations that relieve the enhancing effect of E(spl)D on spl have yielded three classes of mutations: intragenic revertants of the E(spl)D allele, extragenic suppressors that are allelic to the neurogenic gene Delta (Dl) and unlinked extragenic modifiers. Analysis of the suppression of the spl-E(spl)D interaction by various Dl alleles indicates that this modification is sensitive to the dosage of the Dl locus. This tripartite interaction illustrates the combinatorial action of N, Dl and E(spl) during imaginal development.

Alleles↗
PubMed1991

Three neighboring genes interact with the Broad-Complex and the Stubble-stubbloid locus to affect imaginal disc morphogenesis in Drosophila.

The Broad-Complex (BR-C) is a complex regulatory locus at 2B-5 on the X chromosome of Drosophila melanogaster. The wild-type BR-C products are apparent transcription factors necessary for imaginal disc morphogenesis. Alleles of the Stubble-stubbloid (Sb-sbd) locus at 89B9-10 act as dominant enhancers of broad alleles of the BR-C. Sb-sbd wild-type products are necessary for appendage elongation. We report, here, on three new loci implicated in imaginal disc morphogenesis based on their genetic interactions with both BR-C and/or Sb-sbd mutants. Enhancer of broad (E(br)) was identified as a dominant enhancer of the br1 allele of the BR-C and is a recessive lethal. Mapping of E(br) has led to the identification of two loci, blistered and l(2)B485, mutants of which interact with E(br) and the Sb-sbd locus. Blistered, but not l(2)B485, interacts strongly with the BR-C. Alleles of the blistered locus are viable and disrupt proper wing disc morphogenesis independent of genetic interactions. All three loci map within the 0.6-map unit interval between the genetic markers speck and Irregular facets and to the cytological region 60C5-6; 60E9-10 at the tip of chromosome 2R. Genetic evidence is consistent with the view that the BR-C regulates blistered.

Alleles↗
PubMed1998

Analysis of a Drosophila cyclin E hypomorphic mutation suggests a novel role for cyclin E in cell proliferation control during eye imaginal disc development.

We have generated and characterized a Drosophila cyclin E hypomorphic mutation, DmcycEJP, that is homozygous viable and fertile, but results in adults with rough eyes. The mutation arose from an internal deletion of an existing P[w+lacZ] element inserted 14 kb upstream of the transcription start site of the DmcycE zygotic mRNA. The presence of this deleted P element, but not the P[w+lacZ] element from which it was derived, leads to a decreased level of DmcycE expression during eye imaginal disc development. Eye imaginal discs from DmcycEJP larvae contain fewer S phase cells, both anterior and posterior to the morphogenetic furrow. This results in adults with small rough eyes, largely due to insufficient numbers of pigment cells. Altering the dosage of the Drosophila cdk2 homolog, cdc2c, retinoblastoma, or p21(CIP1) homolog dacapo, which encode proteins known to physically interact with Cyclin E, modified the DmcycEJP rough eye phenotype as expected. Decreasing the dosage of the S phase transcription factor gene, dE2F, enhanced the DmcycEJP rough eye phenotype. Surprisingly, mutations in G2/M phase regulators cyclin A and string (cdc25), but not cyclin B1, B3, or cdc2, enhanced the DmcycEJP phenotype without affecting the number of cells entering S phase, but by decreasing the number of cells entering mitosis. Our analysis establishes the DmcycEJP allele as an excellent resource for searching for novel cyclin E genetic interactors. In addition, this analysis has identified cyclin A and string as DmcycEJP interactors, suggesting a novel role for cyclin E in the regulation of Cyclin A and String function during eye development.

Alleles↗
PubMed2000

A screen for new trithorax group genes identified little imaginal discs, the Drosophila melanogaster homologue of human retinoblastoma binding protein 2.

The proteins encoded by two groups of conserved genes, the Polycomb and trithorax groups, have been proposed to maintain, at the level of chromatin structure, the expression pattern of homeotic genes during Drosophila development. To identify new members of the trithorax group, we screened a collection of deficiencies for intergenic noncomplementation with a mutation in ash1, a trithorax group gene. Five of the noncomplementing deletions uncover genes previously classified as members of the Polycomb group. This evidence suggests that there are actually three groups of genes that maintain the expression pattern of homeotic genes during Drosophila development. The products of the third group appear to be required to maintain chromatin in both transcriptionally inactive and active states. Six of the noncomplementing deficiencies uncover previously unidentified trithorax group genes. One of these deficiencies removes 25D2-3 to 26B2-5. Within this region, there are two, allelic, lethal P-insertion mutations that identify one of these new trithorax group genes. The gene has been called little imaginal discs based on the phenotype of mutant larvae. The protein encoded by the little imaginal discs gene is the Drosophila homologue of human retinoblastoma binding protein 2.

Animals↗
PubMed2003

Genetic interactions between the RhoA and Stubble-stubbloid loci suggest a role for a type II transmembrane serine protease in intracellular signaling during Drosophila imaginal disc morphogenesis.

The Drosophila RhoA (Rho1) GTPase is essential for postembryonic morphogenesis of leg and wing imaginal discs. Mutations in RhoA enhance leg and wing defects associated with mutations in zipper, the gene encoding the heavy chain of nonmuscle myosin II. We demonstrate here that mutations affecting the RhoA signaling pathway also interact genetically with mutations in the Stubble-stubbloid (Sb-sbd) locus that encodes an unusual type II transmembrane serine protease required for normal leg and wing morphogenesis. In addition, a leg malformation phenotype associated with overexpression of Sb-sbd in prepupal leg discs is suppressed when RhoA gene dose is reduced, suggesting that RhoA and Sb-sbd act in a common pathway during leg morphogenesis. We also characterized six mutations identified as enhancers of zipper mutant leg defects. Three of these genes encode known members of the RhoA signaling pathway (RhoA, DRhoGEF2, and zipper). The remaining three enhancer of zipper mutations interact genetically with both RhoA and Sb-sbd mutations, suggesting that they encode additional components of the RhoA signaling pathway in imaginal discs. Our results provide evidence that the type II transmembrane serine proteases, a class of proteins linked to human developmental abnormalities and pathology, may be associated with intracellular signaling required for normal development.

Animals↗
PubMed1996

Ectopic E2F expression induces S phase and apoptosis in Drosophila imaginal discs.

Previous experiments suggest that a key event in the commitment of cultured mammalian cells to entering S phase is a rise in activity of the transcription factor E2F. In this report, we study the role of Drosophila E2F in imaginal disc cells in vivo, by examining the distribution of the endogenous protein and studying the consequences of ectopic E2F expression. First, we find that endogenous E217 falls from high to very low levels as cells initiate DNA synthesis during a developmentally regulated G1-S-transition in the eye disc. Second, we find that ectopic E2F expression drives many otherwise quiescent cells to enter S phase. Subsequently, cells throughout the discs express reaper (a regulator of apoptosis) and then die. Third, we find that ectopic E2F expression during S phase in normally cycling cells blocks their re-entry into S phase in the following cell cycle. Although we do not know the fate of these cells, we suspect that ultimately they are killed by ectopic E2F. Taken together, our results show that an elevation in the level of E2F is sufficient to induce imaginal disc cells to enter S phase. Furthermore, they suggest that the downregulation of E2F upon entry into S phase may be essential to prevent the induction of apoptosis.

Animals↗
PubMed2002

A cellular memory module conveys epigenetic inheritance of hedgehog expression during Drosophila wing imaginal disc development.

In Drosophila, the Trithorax-group (trxG) and Polycomb-group (PcG) proteins interact with chromosomal elements, termed Cellular Memory Modules (CMMs). By modifying chromatin, this ensures a stable heritable maintenance of the transcriptional state of developmental regulators, like the homeotic genes, that is defined embryonically. We asked whether such CMMs could also control expression of genes involved in patterning imaginal discs during larval development. Our results demonstrate that expression of the hedgehog gene, once activated, is maintained by a CMM. In addition, our experiments indicate that the switching of such CMMs to an active state during larval stages, in contrast to embryonic stages, may require specific trans-activators. Our results suggest that the patterning of cells in particular developmental fields in the imaginal discs does not only rely on external cues from morphogens, but also depends on the previous history of the cells, as the control by CMMs ensures a preformatted gene expression pattern.

Animals↗
PubMed1989

Expression of achaete and scute genes in Drosophila imaginal discs and their function in sensory organ development.

Several kinds of sensory organs (SOs) appear in stereotyped positions on the adult Drosophila cuticle. The generation of these SOs requires the activity of the achaete (ac) and scute (sc) genes. To investigate whether ac and sc also provide spatial information for the positioning of SOs, we have analyzed the patterns of expression of these genes in the wing imaginal disc around the time that SO precursors are being specified. We find that expression coincides with and is restricted to areas of the disc where these precursors are known to be located. In the loss-of-function sc mutant, sc RNA is depleted in a single area located in the region where the precursor for the suppressed macrochaeta should be found. Moreover, some, and probably all, SOs require expression of these genes to reach the earliest detectable differentiated state. These and other results presented here, together with the finding that expansion of the areas of ac and/or sc expression causes the development of ectopic SOs, indicate that ac and sc promote the determination of SO precursors and delimit the regions of the imaginal discs where they can develop.

Animals↗
PubMed1992

apterous, a gene required for imaginal disc development in Drosophila encodes a member of the LIM family of developmental regulatory proteins.

The apterous (ap) gene is required for the normal development of the wing and haltere imaginal discs in Drosophila melanogaster. ap encodes a new member of the LIM family of developmental regulatory genes. The deduced amino acid sequence of ap predicts a homeo domain and a cysteine/histidine-rich domain known as the LIM domain. In these domains ap is highly similar to the mec-3 and lin-11 proteins of Caenorhabditis elegans and to the vertebrate insulin enhancer-binding protein isl-1. ap is presumably required for transcriptional regulation of genes involved in wing and haltere development. The nature of the defects in homozygous null mutant flies is consistent with the pattern of ap expression in the larval imaginal discs. ap is also expressed in a complex pattern in the embryo, including portions of the peripheral nervous system (PNS) and central nervous system (CNS). A requirement for ap expression in the larval and adult CNS may be the underlying cause of the defects in hormone production and vitellogenesis described for ap mutations.

Amino Acid Sequence↗
PubMed1994

Direct downstream targets of proneural activators in the imaginal disc include genes involved in lateral inhibitory signaling.

In Drosophila imaginal discs, the spatially restricted activities of the achaete (ac) and scute (sc) proteins, which are transcriptional activators of the basic-helix-loop-helix class, define proneural clusters (PNCs) of potential sensory organ precursor (SOP) cells. Here, we report the identification of several genes that are direct downstream targets of ac-sc activation, as judged by the following criteria. The genes are expressed in the PNCs of the wing imaginal disc in an ac-sc-dependent manner; the proximal promoter regions of all of these genes contain one or two high-affinity ac-sc binding sites, which define the novel consensus GCAGGTG(T/G)NNNYY; where tested, these binding sites are required in vivo for PNC expression of promoter-reporter fusion genes. Interestingly, these ac-sc target genes, including Bearded, Enhancer of split m7, Enhancer of split m8, and scabrous, are all known or believed to function in the selection of a single SOP from each PNC, a process mediated by inhibitory cell-cell interactions. Thus, one of the earliest steps in adult peripheral neurogenesis is the direct activation by proneural proteins of genes involved in restricting the expression of the SOP cell fate.

Animals↗
PubMed1994

Diploidy of Drosophila imaginal cells is maintained by a transcriptional repressor encoded by escargot.

The Drosophila escargot (esg) gene encodes a C2-H2-type zinc finger protein that is expressed in the imaginal discs and histoblasts. In some esg mutants, the abdominal histoblasts become polyploid. It has therefore been suggested that the role of esg is to maintain diploidy of the imaginal cells. We show that esg encodes a DNA-binding protein with high affinity for G/ACAGGTG, the consensus-binding sequence for the basic helix-loop-helix (bHLH) family of transcription factors (E2 box). This DNA-binding activity is essential for esg function in vivo as the strong embryonic lethal allele esgVS8 is caused by an amino acid change within the zinc finger region, leading to reduced affinity for DNA. In cultured cells, a heterodimer of the bHLH proteins Scute and Daughterless activates transcription from promoters containing E2 boxes. The esg protein strongly inhibits this activation, suggesting that esg may regulate developmental processes dependent on bHLH proteins. In larvae, esg protein expressed by the heat shock promoter can rescue the polyploid phenotype of abdominal histoblasts, demonstrating that the phenotype is attributable to a loss of esg function. esg must be expressed continuously during the larval period for efficient rescue. Ectopic expression of esg in the salivary glands inhibits endoreplication of DNA. These results suggest that esg is involved in transcriptional inhibition of genes required for endoreplication.

Animals↗
PubMed1995

Dachsous encodes a member of the cadherin superfamily that controls imaginal disc morphogenesis in Drosophila.

Mutations in the dachsous gene of Drosophila lead to striking defects in the morphogenesis of the thorax, legs, and wings. The dachsous gene has been cloned and shown to encode a huge transmembrane protein that is a member of the cadherin superfamily, similar to the fat gene reported previously. Both the Dachsous and Fat proteins contain large tandem arrays of cadherin domains--27 and 34, respectively--as compared with 4 cadherin domains in classic vertebrate cadherins. In addition, Dachsous and Fat each has a cytoplasmic domain with sequence similarity to the cytoplasmic beta-catenin-binding domain of classic vertebrate cadherins. The dachsous gene is expressed in the ectoderm of embryos, whereas its expression in larvae is restricted to imaginal discs and specific regions of the brain. The phenotypes of, and genetic interactions between dachsous and fat are consistent with a model in which cell proliferation and morphogenesis of imaginal structures depends on the coupled equilibria between homo- and heterophilic interactions of the Dachsous and Fat cadherin proteins.

Alleles↗
PubMed2002

The treatment of fear of flying: a controlled study of imaginal and virtual reality graded exposure therapy.

The goal of this study was to determine if virtual reality graded exposure therapy (VRGET) was equally efficacious, more efficacious, or less efficacious, than imaginal exposure therapy in the treatment of fear of flying. Thirty participants (Age = 39.8 +/- 9.7) with confirmed DSM-IV diagnosis of specific phobia fear of flying were randomly assigned to one of three groups: VRGET with no physiological feedback (VRGETno), VRGET with physiological feedback (VRGETpm), or systematic desensitization with imaginal exposure therapy (IET). Eight sessions were conducted once a week. During each session, physiology was measured to give an objective measurement of improvement over the course of exposure therapy. In addition, self-report questionnaires, subjective ratings of anxiety (SUDs), and behavioral observations (included here as flying behavior before beginning treatment and at a three-month posttreatment followup) were included. In the analysis of results, the Chi-square test of behavioral observations based on a three-month posttreatment followup revealed a statistically significant difference in flying behavior between the groups [chi(2) (4) = 19.41, p < 0.001]. Only one participant (10%) who received IET, eight of the ten participants (80%) who received VRGETno, and ten out of the ten participants (100%) who received VRGETpm reported an ability to fly without medication or alcohol at three-month followup. Although this study included small sample sizes for the three groups, the results showed VRGET was more effective than IET in the treatment of flying. It also suggests that physiological feedback may add to the efficacy of VR treatment.

Adult↗
PubMed2004

Use of cognitive versus perceptual heading during imagined locomotion depends on the response mode.

Three experiments investigated whether the systematic errors previously observed in a triangle-completion task were caused by failures to form and update a cognitive heading or by use of perceived heading (even though an updated cognitive heading was available) during the response. These errors were replicated when participants indicated the origin of triangular paths they had imagined walking by turning their bodies toward the origin, but not when they responded verbally. The results indicate that participants are capable of updating their cognitive heading using imagined movements and suggest that the systematic errors previously observed were a result of the strong attachment of responses such as turns to a perceptual representation of the physical body.

Cognition↗
PubMed2006

Juvenile hormone is required to couple imaginal disc formation with nutrition in insects.

In starved larvae of the tobacco hornworm moth Manduca sexta, larval and imaginal tissues stop growing, the former because they lack nutrient-dependent signals but the latter because of suppression by juvenile hormone. Without juvenile hormone, imaginal discs form and grow despite severe starvation. This hormone inhibits the intrinsic signaling needed for disc morphogenesis and does so independently of ecdysteroid action. Starvation and juvenile hormone treatments allowed the separation of intrinsic and nutrient-dependent aspects of disc growth and showed that both aspects must occur during the early phases of disc morphogenesis to ensure normal growth leading to typical-sized adults.

Animal Nutritional Physiological Phenomena↗